package com.algorithm.floyd;

import java.util.Arrays;

/**
 * @author xxy
 * @create 2021 3 27 11:21
 */
public class Floyd {
    public static void main(String[] args) {
        char[] vertex={'A','B','C','D','E','F','G'};
        int[][] matrix=new int[vertex.length][vertex.length];
        final int N=65535;
        matrix[0]=new int[]{0,5,7,N,N,N,2};
        matrix[1]=new int[]{5,0,N,9,N,N,3};
        matrix[2]=new int[]{7,N,0,N,8,N,N};
        matrix[3]=new int[]{N,9,N,0,N,4,N};
        matrix[4]=new int[]{N,N,8,N,0,5,4};
        matrix[5]=new int[]{N,N,N,4,5,0,6};
        matrix[6]=new int[]{2,3,N,N,4,6,0};
        Graph graph = new Graph(vertex.length,matrix,vertex);
        graph.floyd();
        graph.show();


    }
}
class Graph{
    private char[] vertex;
    private int[][] dis;
    private int[][] pre;
    public Graph(int length,int[][] matrix,char[] vertex){
        this.vertex=vertex;
        this.dis=matrix;
        this.pre=new int[length][length];
        //对pre 数组进行初始化，注意存放的是前驱结点的下标
        for(int i=0;i<length;i++){
            Arrays.fill(pre[i],i);
        }
    }
    public void floyd(){
        int len=0;//变量保存距离
        //对中间结点遍历，k就是中间顶点的下标
        for (int k = 0; k < dis.length; k++) {
            //从i顶点开始出发，
            for (int i = 0; i < dis.length; i++) {
                //从i顶点开发经过k到达j
                for (int j = 0; j < dis.length; j++) {
                    len=dis[i][k]+dis[k][j];
                    if(len<dis[i][j]){
                        //如果len小于直连，就更新
                        dis[i][j]=len;
                        pre[i][j]=pre[k][j];
                    }
                }
            }
        }
    }
    public void show(){
        char[] vertex={'A','B','C','D','E','F','G'};
        for (int k = 0; k < dis.length; k++) {
            for(int i=0;i<dis.length;i++){
                System.out.print(vertex[pre[k][i]]+" ");
            }
            System.out.println();
            //输出dis数组
            for(int i=0;i<dis.length;i++){
                System.out.print("("+vertex[k]+"->"+vertex[i]+")"+"="+dis[k][i]+" ");
            }
            System.out.println();
        }
    }
}